Fix unhandled ArgumentOutOfRangeException when exporting FlameGraph with unrendered canvas by Copilot · Pull Request #2339 · microsoft/perfview

Copilot · 2025-11-21T02:17:05Z

Summary

Fixed unhandled ArgumentOutOfRangeException that occurred when saving a FlameGraph with an unrendered or invalid-sized canvas. The fix includes:

Input validation: Added checks in FlameGraph.Export() to ensure canvas width and height are greater than zero before creating RenderTargetBitmap
Proper exception type: Uses ArgumentOutOfRangeException which matches the original error from RenderTargetBitmap
Graceful error handling: Wrapped the export call in a try-catch block to display user-friendly error messages via StatusBar.LogError()
User feedback: Added success message when flame graph is saved successfully
Test coverage: Added unit test to verify the fix
Best practices: Uses nameof() operator for parameter names

All review comments have been addressed. The changes are minimal, focused, and directly address the reported issue.

Original prompt

This section details on the original issue you should resolve

<issue_title>Unhanded exception while trying to Save Flame Graph</issue_title>
<issue_description>I apologize for not sharing the offending ETL file, it contains proprietary information.

An unhanded exception occured.

. . .

The fact that this exception went unhanded is a programmer error.   It should be reported so it can be fixed.  Please set along the following stack trace information which will be useful in diagnosing the problem.

StackTrace:
System.ArgumentOutOfRangeException: The parameter value must be greater than zero.
Parameter name: pixelWidth
   at System.Windows.Media.Imaging.RenderTargetBitmap..ctor(Int32 pixelWidth, Int32 pixelHeight, Double dpiX, Double dpiY, PixelFormat pixelFormat)
   at PerfView.FlameGraph.Export(Canvas flameGraphCanvas, String filePath)
   at PerfView.StackWindow.DoSaveFlameGraph(Object sender, RoutedEventArgs e)
   at System.Windows.Input.CommandBinding.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
   at System.Windows.Input.CommandManager.ExecuteCommandBinding(Object sender, ExecutedRoutedEventArgs e, CommandBinding commandBinding)
   at System.Windows.Input.CommandManager.FindCommandBinding(CommandBindingCollection commandBindings, Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
   at System.Windows.Input.CommandManager.FindCommandBinding(Object sender, RoutedEventArgs e, ICommand command, Boolean execute)
   at System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
   at System.Windows.Input.CommandManager.TransferEvent(IInputElement newSource, ExecutedRoutedEventArgs e)
   at System.Windows.Input.CommandManager.OnExecuted(Object sender, ExecutedRoutedEventArgs e)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
   at System.Windows.Input.RoutedCommand.ExecuteImpl(Object parameter, IInputElement target, Boolean userInitiated)
   at MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated)
   at System.Windows.Controls.MenuItem.InvokeClickAfterRender(Object arg)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)
```</issue_description>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

Fixes Unhanded exception while trying to Save Flame Graph #2245

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

…t namespace usage Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Brian Robbins (brianrob)

Copilot, please address these comments.

Brian Robbins (brianrob) · 2025-11-21T04:53:26Z

+            // Validate that the canvas has a valid size before attempting to export
+            if (width <= 0 || height <= 0)
+            {
+                throw new InvalidOperationException(


Suggested change

throw new InvalidOperationException(

throw new ArgumentOutOfRangeException(

Done in 0699b4a

Brian Robbins (brianrob) · 2025-11-21T04:54:06Z

+            {
+                throw new InvalidOperationException(
+                    $"Cannot export flame graph: the canvas has an invalid size (width={width}, height={height}). " +
+                    "Please ensure the flame graph is visible and has been rendered before attempting to export.");


The text here is too long to appear in the status bar. Please use this text: "Please ensure the flame graph is visible and has been rendered before attempting to export."

Done in 0699b4a - shortened the error message to just the essential guidance

Brian Robbins (brianrob) · 2025-11-21T04:54:30Z

+                    FlameGraph.Export(FlameGraphCanvas, saveDialog.FileName);
+                    StatusBar.Log($"Saved flame graph to {saveDialog.FileName}");
+                }
+                catch (InvalidOperationException ex)


Suggested change

catch (InvalidOperationException ex)

catch (ArgumentOutOfRangeException ex)

Done in 0699b4a

Brian Robbins (brianrob) · 2025-11-21T04:54:46Z

+            try
+            {
+                // Attempt to export should throw InvalidOperationException with a meaningful message
+                var exception = Assert.Throws<InvalidOperationException>(() =>


Suggested change

var exception = Assert.Throws<InvalidOperationException>(() =>

var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>

Done in 0699b4a

…r message Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Copilot · 2025-11-21T04:57:42Z

Copilot, please address these comments.

All review comments addressed in commit 0699b4a:

Changed exception type from InvalidOperationException to ArgumentOutOfRangeException
Shortened error message text
Updated catch block and test to match new exception type

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Brian Robbins (brianrob)

Copilot, please address these comments.

Brian Robbins (brianrob) · 2025-11-21T05:14:39Z

+            {
+                throw new ArgumentOutOfRangeException(
+                    "flameGraphCanvas",
+                    $"canvas has an invalid size (width={width}, height={height}). Please ensure the flame graph is visible and has been rendered before attempting to export.");


Suggested change

$"canvas has an invalid size (width={width}, height={height}). Please ensure the flame graph is visible and has been rendered before attempting to export.");

$"Canvas has an invalid size (width={width}, height={height}). Please ensure the flame graph is visible and has been rendered before attempting to export.");

Done in 9f9e872

Brian Robbins (brianrob) · 2025-11-21T05:14:46Z

+                });
+
+                // Verify the exception message is helpful
+                Assert.Contains("canvas has an invalid size", exception.Message);


Suggested change

Assert.Contains("canvas has an invalid size", exception.Message);

Assert.Contains("Canvas has an invalid size", exception.Message);

Done in 9f9e872

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Copilot · 2025-11-21T05:17:38Z

Copilot, please address these comments.

Both review comments addressed in commit 9f9e872 - capitalized 'Canvas' in error message and test assertion

Lee Culver (leculver)

One nitpick, but otherwise looks good to me.

Initial plan

f89aa05

Copilot AI assigned Copilot and Brian Robbins (brianrob) Nov 21, 2025

Copilot started work on behalf of Brian Robbins (brianrob) November 21, 2025 02:17

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Copilot AI and others added 2 commits November 21, 2025 02:25

Add validation for FlameGraph export with invalid canvas size

be6c536

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Address code review feedback - use string interpolation and consisten…

1320239

…t namespace usage Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix unhandled exception while saving flame graph~~ Fix unhandled ArgumentOutOfRangeException when exporting FlameGraph with unrendered canvas Nov 21, 2025

Copilot finished work on behalf of Brian Robbins (brianrob) November 21, 2025 02:29

Copilot AI requested a review from Brian Robbins (brianrob) November 21, 2025 02:29

Brian Robbins (brianrob) reviewed Nov 21, 2025

View reviewed changes

Copilot started work on behalf of Brian Robbins (brianrob) November 21, 2025 04:55

View session

Change exception type to ArgumentOutOfRangeException and shorten erro…

0699b4a

…r message Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Fix capitalization in error message for consistency

f684ba5

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Copilot AI requested a review from Brian Robbins (brianrob) November 21, 2025 05:00

Copilot finished work on behalf of Brian Robbins (brianrob) November 21, 2025 05:00

Brian Robbins (brianrob) reviewed Nov 21, 2025

View reviewed changes

Copilot started work on behalf of Brian Robbins (brianrob) November 21, 2025 05:15

View session

Capitalize 'Canvas' in error message per review feedback

9f9e872

Co-authored-by: brianrob <6210322+brianrob@users.noreply.github.com>

Copilot AI requested a review from Brian Robbins (brianrob) November 21, 2025 05:18

Copilot finished work on behalf of Brian Robbins (brianrob) November 21, 2025 05:18

Brian Robbins (brianrob) marked this pull request as ready for review November 21, 2025 05:20

Brian Robbins (brianrob) requested review from Steve Molloy (StephenMolloy), Jiri Cincura ↹ (cincuranet), Lee Culver (leculver), Mark Miller (marklio) and Matt Connew (mconnew) as code owners November 21, 2025 05:20

Lee Culver (leculver) previously approved these changes Nov 21, 2025

View reviewed changes

Comment thread src/PerfView/StackViewer/FlameGraph.cs Resolved

Copilot started work on behalf of Lee Culver (leculver) November 21, 2025 13:41

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	throw new InvalidOperationException(
	throw new ArgumentOutOfRangeException(

	catch (InvalidOperationException ex)
	catch (ArgumentOutOfRangeException ex)

	var exception = Assert.Throws<InvalidOperationException>(() =>
	var exception = Assert.Throws<ArgumentOutOfRangeException>(() =>

	$"canvas has an invalid size (width={width}, height={height}). Please ensure the flame graph is visible and has been rendered before attempting to export.");
	$"Canvas has an invalid size (width={width}, height={height}). Please ensure the flame graph is visible and has been rendered before attempting to export.");

	Assert.Contains("canvas has an invalid size", exception.Message);
	Assert.Contains("Canvas has an invalid size", exception.Message);

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Copilot AI commented Nov 21, 2025 •

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